1. Field of the Invention
The present invention relates to a method for manufacturing a weather strip having a hollow seal portion, which is exemplified by, for example, an opening trim weather strip mounted along the peripheral edge of a door opening portion of a vehicle or the like, and also relates to a molding device for a weather strip.
2. Description of Related Art
Hitherto, there has been known a weather strip that has, for example, a cross-sectionally and substantially U-shaped trim portion and a hollow seal portion bulging outwardly from a side wall part or a bottom wall part of the trim portion. Generally, such a weather strip is formed substantially like a ring by joining end parts of one or plural extruded portions formed by extrusion so as to be elongated. That is, in a condition in which the end parts of the extruded portions are supported and fixed in a molding device, a molded portion is formed between the end parts by injection-molding. Thus, the end parts are connected to each other, so that an annular weather strip is formed.
Also, a nonannular weather strip, in which a molded portion is formed at an end part of an extruded portion, has been known. In this case, a terminal portion of the weather strip is constituted by the molded portion, the shape of a cross-section of which gradually changes.
Meanwhile, in the case of the weather strip of the type, which has the molded portion as described above, when the molded portion is formed, it is necessary to preliminarily dispose a core mold member (hereunder abbreviated as a core mold) for forming the hollow seal portion in a cavity of the molding device. This core mold comprises a core body for sealing the seal portion, and also comprises a grip portion protruding from the core body to the outside. Most of the core body is enclosed by an elastic material, such as rubber. Upon completion of molding the molded portion, the core body needs to be drawn out of a molded article. In this case, usually, an opening (or slit) is provided in the molded portion so as to draw the core body from the molded portion when molded.
Generally, it is desirable from the viewpoint of easiness in drawing out the core body to enlarge the slit as much as possible. However, this causes a demerit that the longer the slit becomes, the shape holding performance thereof and the sealing performance of the seal portion are degraded. The technique of longitudinally dividing the core mold member into plural parts (see, for example, JP-UM-A-3-39514) is known as that of eliminating such a defect. According to this technique, first, one of divided core mold members (hereunder abbreviated as a divided core mold) is drawn out therefrom. This enables the remaining divided core molds and a molded article to perform relative displacement. Thus, even when the slit is not elongated very much, the core body can relatively easily be drawn out of the seal portion of the molded portion.
However, according to the aforementioned technique, the divided core molds differ from other kinds of mold members and are relatively susceptive to physically external forces. Thus, when molding is repeatedly performed, the divided core molds are susceptive to damage. Therefore, the divided core molds need performing frequent maintenance operations and may cause increase the cost thereof. Further, the fact is that according to some configuration of the molding device, even when the core mold is divided, it is still difficult to draw a divided core mold therefrom.